WASHINGTON (AP) — They thought it was impossible. Some still fear it. Others can barely believe it. But leading Republicans are beginning to accept the idea that Donald Trump will be their party's presidential nominee.

In the wake of the businessman's commanding wins in five Eastern states this week, a growing number of national Republicans and GOP lawmakers on Capitol Hill say Trump has taken on an indisputable air of inevitability. Some argue they should get behind him now and abandon the "Never Trump" efforts still nursed by some establishment Republicans. Embracing Trump, these Republicans say, may be the GOP's only hope of blocking Democrat Hillary Clinton in November.

"Donald Trump is going to be our nominee," Florida Gov. Rick Scott wrote on Facebook this week. "The Republican leaders in Washington did not choose him, but the Republican voters across America did choose him. The voters have spoken."

"Republicans now need to come together," Scott wrote, warning that continued opposition to Trump "will be nothing more than a contribution to the Clinton campaign."

On Capitol Hill, support for Trump has also gotten markedly easier to find.

"I don't understand. I mean, it's not 'Never Trump.' It's 'Never Hillary.' Never, never, never Hillary. Come on. Wake up and smell the coffee," said Rep. Mike Kelly of Pennsylvania, who earlier this week cast his ballot for Trump, along with all members of his large family and 57 percent of Republican primary voters in his state.

"I've never seen a party attack one of its own candidates with this aggressiveness," Kelly said of GOP establishment figures who oppose Trump, blaming it on an elitist Washington attitude out of touch with voters.

Sen. Orrin Hatch of Utah, a respected senior member of the Senate, previously endorsed Jeb Bush and then Sen. Marco Rubio and said he doesn't intend to endorse Trump. But Hatch said of Trump, "It looks to me like he's going to win, and if he does, I'm going to do everything in my power to help him."

Some leading Republicans have forecast that a Trump candidacy could spell electoral disaster, help Democrats win back control of the Senate and even cost safe Republican seats in the House. They point to Trump's disparaging comments about women and minorities that have contributed to high unfavorability ratings.

Hatch, along with others, disagreed.

"I think he could be great if he'll get serious about being president, and I think he will," Hatch said. "When he gets hit with reality that this is the toughest job in the world, he's a clever, smart guy who I think will want to be remembered for doing good things, so I have a feeling he can make that transition."

On Thursday, Trump picked up endorsements from two House committee chairmen: Reps. Bill Shuster of Pennsylvania, who chairs the Transportation Committee, and Jeff Miller of Florida, who chairs Veterans Affairs. He talked foreign policy in a phone call with Sen. Bob Corker, R-Tenn., who heads the Foreign Relations Committee. Corker later was full of compliments about Trump, though he said he had no plans to endorse him.

To be sure, not all are on board. Some in the GOP continue to cringe at the thought of vulnerable Senate Republicans and candidates getting linked to Trump's provocative stances or attempting to distance themselves from them.

"My feeling about Donald Trump is, I don't think that that's our best foot forward at all," said Sen. Jeff Flake of Arizona, an outspoken Trump critic. "And I can't imagine being forced to take some of those positions that he's taken. A ban on Muslims, build a wall and make the Mexicans pay for it, you name it."

It remains uncertain whether Trump will amass the 1,237 delegates needed to clinch the nomination ahead of the Republican convention in Cleveland in July. If he does not, Texas Sen. Ted Cruz hopes to make a play to win the nomination as balloting progresses. Ohio Gov. John Kasich also remains in the race. Next week's primary in Indiana, where polling suggests a close race, could be crucial in determining whether either Cruz or Kasich can continue to argue they have a path forward.

Roger Villere, longtime Louisiana state GOP chief and one of the national party's vice chairmen, said a "clear supermajority" at the Republican National Committee spring meeting earlier this month in South Florida were warming to the idea of Trump as standard-bearer.

"There were a lot of them who Trump wasn't their first choice, but when we got in closed rooms and everybody started talking, the general consensus was that he's going to be our nominee, and we will rally around him," Villere said Friday. "I wouldn't say it was even reluctance. It's just the reality."

Offering a common party refrain, Villere added, "All of our possibilities are clearly superior to what the Democrats have."